The "free" data only applies to mobile data when the DTVN app is running on a mobile device (phone or tablet). It doesn't apply to wired (ISP) internet service, or to mobile data when consumed by another device running DTVN (TV streaming device or computer). This is detailed in the various help pages and such that spell out the actual terms.
Award for Community Excellence 2019 Achiever* *The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.